Method for testing the leak-tightness of flexible containers and system for testing the leak-tightness

Abstract

The invention relates to a method for testing the leak-tightness of a flexible container filled with a liquid, in particular an infusion bag. First, an overpressure p1 is generated in the container by advancing a pressing device such that the container is pre-stretched. The pressing device is then retracted. After the pressing device has been retracted, an overpressure p2, which is lower than the overpressure p1, is measured in the pre-stretched container. A leak can be determined if a drop in the pressure p2 is measured in the container.

Description

[0001] Method for testing the tightness of flexible containers and system for testing the tightness

[0002] Description

[0003] Field of invention

[0004] The invention relates to a method for testing the leak tightness of a flexible container filled with a liquid. In particular, the invention relates to a method for testing the leak tightness of infusion bags that are sterilely packaged in secondary packaging. The invention further relates to a container tested by the method. The invention also relates to a system for testing the leak tightness of flexible containers.

[0005] Background of the invention

[0006] High standards are applied to the quality and safety of medical products during their manufacture. Quality control includes, in particular, testing the infusion bag for leaks. For example, a leak test can be performed by weighing the infusion bag during the production process, especially after it has been filled and sealed.

[0007] Infusion bags are usually packaged sterilely in a secondary packaging, such as a tear-open pouch. For sterilization, the infusion bag is autoclaved in the sealed secondary packaging.

[0008] The thermal stress may now cause leaks that were not present before autoclaving. Testing by weighing is not possible because any escaping liquid collects in the secondary bag, so the product's weight remains unchanged.

[0009] Document US 6,439,032 Bl discloses a test procedure in which a force is applied to the infusion bag by means of a test object. An equilibrium is established between the force applied by the test object and the restoring force exerted by the infusion bag. If a leak is present, the restoring force decreases, and the leak can be detected by measuring the force.

[0010] However, it has turned out that with such a method it is difficult to detect even small leaks, especially openings with a maximum diameter of less than 250 pm.

[0011] Object of the invention

[0012] In contrast, the invention is based on the objective of providing a method for testing the tightness of flexible containers, or a system designed for this purpose, with which a simple and accurate test of the tightness of the flexible container is possible. In particular, it is an objective of the invention to detect even small leaks in an infusion bag that is sterilely packaged in a secondary container.

[0013] Summary of the invention

[0014] The object of the invention is achieved by a method for testing the leak tightness of a flexible container filled with a liquid, and by a system for testing the leak tightness of flexible containers filled with a liquid, according to one of the independent claims. Preferred embodiments and further developments of the invention can be found in the subject matter of the dependent claims, the description, and the drawings.

[0015] The invention relates to a method for testing the tightness of a flexible container filled with a liquid, in particular an infusion bag, wherein an overpressure pl is first generated in the container by advancing a pressing device, so that the container is pre-stretched, and wherein the pressing device is then retracted, and wherein after retraction of the pressing device a lower overpressure p2 compared to the overpressure pl is measured in the pre-stretched container, so that a leak can be determined on the basis of a measured pressure drop of p2 and / or a measured volume loss at p2 in the container.

[0016] It has been found that pre-expanding the container, thereby generating a higher pressure inside the container than during the subsequent measurement, results in a more uniform pressure profile during measurement in a sealed container.

[0017] The inventors assume that pre-stretching leads to a change in the macromolecular structure of the polymer material used. It is possible that molecular chains align themselves through pre-pressing, thereby reducing the deformation of the container during measurement due to temporary structural changes.

[0018] This allows even smaller leaks to be detected with greater reliability, and a container with a leak can be sorted out. It is understood that the method according to the invention is non-destructive; provided the container is in secondary packaging, such as a tear-off bag, the secondary packaging does not need to be opened.

[0019] The tightness of the container can be checked by measuring the overpressure p2. If the container is leaking, the overpressure p2 will decrease during the measurement due to the escaping gas and / or liquid.

[0020] In another embodiment, it is also possible to keep the overpressure p2 constant, e.g., by applying pressure with a constant force F2 using the press device. If the container leaks, the press device will compress due to a loss of volume in the container. By measuring the displacement of the press device, a leak can be detected.

[0021] In a further embodiment, it is also possible to combine both measurement methods described above.

[0022] The overpressure pl and the overpressure p2 can be generated by the pressing device in a path-based manner according to a first simple embodiment of the invention.

[0023] The container can, for example, be placed between two plates that serve as a pressing device. The plates are moved together a predefined distance to pre-stretch the container. Then the plates are moved apart slightly to take a measurement at the overpressure p2.

[0024] Whether the restoring force of the container is reduced by a leak at overpressure p2 can be determined, for example, by the restoring force acting on the pressing device. Preferably, the pressure drop of p2 in the container is determined by a force applied to the pressing device.

[0025] The force applied to the pressing device corresponds to the restoring force of the container, which is at least approximately proportional to the pressure present in the container.

[0026] A sensor enables precise force measurement. Examples of sensors include a piezoelectric sensor and / or a strain gauge.

[0027] Preferably, the compression of the container and the determination of the leakage are carried out in the same pressing device.

[0028] The press device used to generate the overpressure pl can be retracted, thus pre-expanding the container. The press device then retracts slightly, and a measurement is taken to determine whether the overpressure p2 drops within a predetermined measuring window to such an extent that a leak can be inferred.

[0029] However, it has turned out that, depending on the container to be tested and / or the system configuration, it is also possible to first pre-expand the container with the overpressure pl, then open the pressing device and then transport the container to a second pressing device, by means of which the overpressure p2 is generated and the measurement is carried out.

[0030] It is assumed that, as explained above, the polymers of the container seemingly temporarily retain the properties altered by the pre-stretching. Preferably, however, the process is carried out in such a way that the pressure pl is so low that no permanent structural changes, in particular plastic deformations, of the container occur.

[0031] As described above, generating the overpressure pl and the overpressure p2 can be achieved via force measurement. The pressing device is advanced until a force Fl is reached and then retracted until a force F2 is applied to the pressing device. F2 is proportional to the overpressure p2.

[0032] The force during pre-stretching, i.e., the force Fl, is, according to a preferred embodiment of the invention, 1.1 to 5 times, preferably 1.5 to 3.5 times, and particularly preferably 1.8 to 2.8 times, as large as the force F2. The same ratios preferably apply to the ratio of the overpressure pl to the overpressure p2.

[0033] In one embodiment of the invention, F2 lies between 20 and 300 N, in particular between 50 and 180 N.

[0034] According to one embodiment, the initial overpressure p2 during the measuring window, i.e. when measuring the pressure drop or volume loss, is between 0.02 and 1 bar, preferably between 0.05 and 0.3 bar and particularly preferably between 0.07 and 0.11 bar.

[0035] The overpressure pl during pre-stretching is, according to a

[0036] In one embodiment, the pressure is between 0.02 and 1 bar, preferably between 0.15 and 0.3 bar, particularly preferably between 0.20 and 0.25 bar. According to another embodiment, the container is pre-stretched for 0.1 to 10 s, preferably 1 to 5 s, particularly preferably 2 to 3.5 s.

[0037] The overpressure p2, which decreases in the event of a leak, is preferably measured over a time interval of 0.1 to 10 s, preferably 1 to 5 s, particularly preferably 2.5 to 4 s.

[0038] The overpressure p2 is preferably measured within less than 60 minutes, particularly preferably within less than 5 minutes, and most preferably within less than 1 minute after pre-expansion of the container. In particular, the pressure p2 is measured immediately after pre-expansion. A stable overpressure p2 should have been established. According to one embodiment, at least 0.5 seconds is allowed to pass after the compression device has retracted before the measuring window begins.

[0039] According to one embodiment of the invention, the container is provided sterile in a secondary packaging. The secondary packaging is, in particular, designed as a tear-open pouch. Specifically, the container is a container that has been autoclaved with a medical liquid in the sealed secondary packaging.

[0040] The medical fluid could be, for example, an infusion solution or a preparation for enteral or parenteral nutrition.

[0041] In one embodiment of the invention, the liquid in the container has a temperature of 30 to 80°C, preferably 35 to 65°C, during the measurement. Thus, a container still warm from autoclaving is preferably tested. This ensures a fast process time and eliminates the need to temporarily store the containers to cool down before testing for leaks.

[0042] It has been found that the pre-stretching according to the invention can have an increasing effect on the accuracy of the measuring method as the temperature of the container increases.

[0043] Such a container, in particular an infusion bag containing a medicinal fluid, may include at least one port. Specifically, such containers have a withdrawal port for transferring the medicinal fluid into the patient using a transfer set, and preferably also an injection port for transferring, for example, pharmaceutical active substances into the interior of the container.

[0044] Such a port can comprise a lower part that is welded into the container. In one embodiment, an upper part is placed on the lower part to close the container, with a sealing element inserted between the upper and lower parts. To dispense or inject liquid, the sealing element can be pierced with a spike or needle. Preferably, the sealing element is designed such that it reseals itself after the spike or needle is removed.

[0045] It has been found that smaller leaks, in particular, can occur in the port area. Leakage points can be found at the welds, most often in the area where the lower part is welded in.

[0046] According to one embodiment of the invention, the method is therefore carried out in such a way that the port is oriented upwards during the measurement of the overpressure p2 or the volume loss at p2.

[0047] This can be done, for example, by placing items lying flat on a belt

[0048] The container should be rotated approximately 90° so that the port is at the top.

[0049] The entire port, including the lower part, is located adjacent to the gas volume present in the container. Since gas escapes from an opening faster than liquid (at the same pressure), leaks in the port area, even those in the micrometer range, can be detected.

[0050] The method according to the invention relates in particular to the testing of containers which are made of a multilayer film, in particular of a polyolefin film, such as a polypropylene film.

[0051] At least one, and in particular all, layers of the film can be configured as a matrix-phase polymer system. In a matrix-phase polymer system, at least two different polymers are present, one of which is present in a segregated form, in particular as dispersed solidified droplets, within the matrix of the other polymer.

[0052] The matrix polymer of the matrix-phase polymer system of the inner layer, the middle layer, and the outer layer each comprises a polypropylene polymer. In particular, the matrix consists of a polypropylene.

[0053] The phase polymer of the matrix-phase polymer system of the inner layer, the middle layer, and the outer layer can each comprise at least one styrene-ethylene / butylene-styrene block copolymer (SEBS) as a phase polymer. SEBS is a block polymer composed of styrene, butylene, and ethylene segments, comprising a hydrogenated butadiene segment to which styrene groups are attached. It is produced, in particular, by polymerization of a styrene and butadiene monomer followed by hydrogenation of the previously polymerized SBS. The hydrogenated butadiene forms a soft middle block between styrene blocks. The SEBS bonds with the PP matrix polymer.

[0054] Such a multi-layer system allows for the use of different components and / or compositions in the respective layers to produce highly transparent and at the same time very tear-resistant films that can be easily welded into a bag.

[0055] The method according to the invention is preferably used to sort out containers which are detected due to a pressure drop or volume loss during the measuring window at pressure p2.

[0056] In particular, containers with an opening with a diameter of less than 150 pm (maximum diameter) can be sorted out.

[0057] The invention further relates to a container, in particular an infusion bag, which was tested using the method described above.

[0058] According to a further aspect of the invention, the invention relates to a system for testing the leak tightness of flexible containers filled with a liquid. The system is specifically designed to carry out the method described above.

[0059] The system comprises a receiving space for at least one container, a pressing device by means of which the container arranged in the receiving space can be compressed, wherein the pressing device includes a force measuring device for measuring a pressing force acting on the container.

[0060] The system includes a control unit, in particular for carrying out the method described above according to the invention.

[0061] In one version, the receiving chamber together with the pressing device can be pivoted between a horizontal and a vertical position.

[0062] The invention can also be described as follows: The system comprises a receiving space for at least one container, a pressing device by means of which the container arranged in the receiving space can be compressed, wherein the pressing device comprises a force measuring device for measuring a pressing force acting on the container, and wherein the receiving space together with the pressing device is pivotable between a horizontal and a vertical position.

[0063] The receiving space can be formed in particular by the pressing device.

[0064] For example, the pressing device can include a plate that presses down on the container lying in the receiving space.

[0065] A force sensor, for example a measuring cell, can be arranged between the plate and an actuator for moving the pressing device. The actuator can be, for example, an electric or pneumatic actuator. The receiving chamber is designed in such a way that at least one flat container can be inserted into the receiving chamber and then moved into a vertical position within the receiving chamber.

[0066] Preferably, the entire receiving space, including the pressing device and force measuring device, is swivelled for this purpose.

[0067] The system according to the invention makes it easy to feed containers filled in an automated device, packaged in secondary packaging, and then sterilized, into the system in a flat position and then pivot them into a vertical position so that the gas volume is located in the area of ​​the port(s) of the container during the leak test. This allows the accuracy of the measurement to be increased in a simple way.

[0068] In a further development of the invention, the system is part of a transport system.

[0069] In particular, the receiving space opposite the pressing device is limited by a conveying device, especially a conveyor belt for the container.

[0070] The conveying device is pivoted into the vertical position along with at least one container.

[0071] The pressing device can be formed, in particular, by a movable plate located opposite the conveying device. The system is therefore designed such that one or more containers are first moved into the system one after the other by means of the conveying device.

[0072] The containers can be fed into the system, for example, via another conveying device, in particular a conveyor belt of a transport system. The conveying device then stops, and the conveying device of the system, as part of the receiving area, is pivoted into a vertical position with the container(s).

[0073] The container can be pre-stretched at least partially before and / or during the swiveling process.

[0074] A leak test can then be carried out, in particular using the procedure described above.

[0075] The force measuring device, which operates, for example, piezoelectrically or according to the principle of a strain gauge, measures the force acting on the pressing device, in particular on the plate.

[0076] The system may include a control unit designed to execute the procedure described above.

[0077] In particular, the control device may include a memory on which a program is stored that executes the process steps described above.

[0078] The system according to the invention is used for testing containers, in particular infusion bags, for leaks.

[0079] Brief description of the drawings: The subject matter of the invention will be explained in more detail below with reference to the drawings Fig. 1 to Fig. 11.

[0080] Fig. 1 shows an embodiment of a container.

[0081] Fig. 2 is a schematic representation of the measuring method on which the invention is based.

[0082] Fig. 3 shows the course of the restoring force of non-pre-stretched containers.

[0083] Fig. 4 shows the course of the restoring force of pre-stretched containers.

[0084] Fig. 5 is a representation of the force curve in the test method according to the invention.

[0085] Fig. 6 and Fig. 7 show the dispersion of the pressure loss of a sealed container and of two different containers with a leak.

[0086] Fig. 8 is a flowchart of an embodiment of the method according to the invention.

[0087] Fig. 9 schematically shows a container placed in a press.

[0088] Fig. 10 is a side view of a system according to the invention for testing containers for leaks.

[0089] Fig. 11 shows the system depicted in Fig. 10 in the position pivoted into a vertical position.

[0090] Detailed description of the drawings Fig. 1 shows an exemplary embodiment of a container 10, which is designed as an infusion bag 10.

[0091] The infusion bag 10 includes ports 11a and 11b, with port 11a being configured as an injection port and port 11b as a withdrawal port.

[0092] The ports each comprise a lower part 12, on which an upper part 13 is placed.

[0093] Between the upper part 13 and the lower part 12 there is a sealing element (not shown) which can be pierced to remove or inject liquid.

[0094] In this embodiment, the upper part 13 is each closed with a snap-off cap 14, which can be removed before using the infusion bag 10.

[0095] The infusion bag 10 is formed from two films which are connected to each other via longitudinal weld seams 15 and transverse weld seams 16.

[0096] The lower part 12 of a port 11a, 11b is each welded into the transverse weld 16.

[0097] It has been found that minor leaks can occur, especially in the area of ​​ports 11a and 11b.

[0098] The infusion bag 10 is placed in a secondary packaging 20, which is designed as a tear-off bag.

[0099] For this purpose, the secondary packaging can, for example, include a notch 22. The secondary packaging 20 is designed as a film bag, which is formed by films joined via longitudinal weld seams 21 and transverse weld seams 23.

[0100] The infusion bag 10 is arranged sterilely in the sealed secondary packaging 20, as it was autoclaved in the sealed secondary packaging.

[0101] Fig. 2 schematically shows the underlying measurement principle.

[0102] For this purpose, the container 10 or the container 10 packed in the secondary packaging 20 is placed in a pressing device.

[0103] Pressure is exerted on the container 10 via a measuring cell 101 by means of an actuator 102.

[0104] The restoring force applied by the container 10 is measured via the measuring cell 101. This restoring force corresponds to the force with which the actuator 102 presses on the container 10 and which is proportional to the overpressure p2.

[0105] If the container 10 has a leak, gas or liquid escapes into the secondary packaging 20, thus reducing the volume of the container 10. This decreases the restoring force of the container 10, which can be detected by the measuring cell 101. Threshold values ​​can therefore be defined, for example, above which a leak is inferred.

[0106] Fig. 3 shows the force / time curve in a measurement window for various containers. Time in ms is plotted on the x-axis and force in N on the y-axis. The containers measured here were not pre-stretched.

[0107] As explained above, the force is proportional to the pressure inside the container. The upper curve shows a sealed container at 20°C. The lower curve shows a sealed container at 60°C.

[0108] Although the containers are sealed, a loss of force and thus a loss of pressure occurs in the measuring window, which is significantly greater in the case of the 60°C warm container.

[0109] This pressure loss is superimposed on the pressure loss caused by small leaks, so that such smaller leaks cannot be detected, especially when the container is warm.

[0110] Fig. 4 shows, corresponding to Fig. 3, the force / time curve of containers at 60°C (curves above) and 20°C (curves below) which were pre-stretched using the method according to the invention.

[0111] The diagram shows that in both the 60°C and 20°C containers, the force and thus the pressure stabilizes so effectively after a period of 0.5 to 1 s that an almost linear curve is observed.

[0112] Because of this linear progression, smaller leaks due to pressure loss can be significantly detected.

[0113] Fig. 5 shows an example of a force / time curve. Time is dimensionless on the x-axis and force in N is plotted on the y-axis.

[0114] In phase 1, the force is increased by means of the pressing device until, in phase 2, the overpressure pl is reached for pre-expansion of the container. The force Fl is maintained for a pre-programmed time window (phase 2).

[0115] In phase 3, the force is reduced until the lower overpressure p2, which corresponds to the force F2, is reached.

[0116] (Phase 3) .

[0117] The measurement window (phase 4) can begin at the latest when the force F2, which is measured by the measuring cell, has stabilized.

[0118] The upper curve represents the force profile of a dense container.

[0119] As shown in Fig. 4, the force F2 and thus the overpressure p2 remain almost constant during the measuring window. The container is leak-proof.

[0120] The lower curve shows the course of the force F2 as a function of the overpressure p2 in a container with a leak. The overpressure p2, and therefore the force F2, decreases, indicating a leak.

[0121] Fig. 6 shows the scatter of the overpressure p2 at the end of the measurement for containers at 40 °C with various leakage rates. The curve on the left shows the force loss of leaking containers with a 200 pm hole during the measurement window, the curve in the middle the force loss of leaking containers with a 100 pm hole, and the curve on the right the force at the end of the measurement for leak-proof containers.

[0122] The x-axis represents the force loss in N (corresponding to the pressure loss of the gauge pressure p2), and the y-axis represents the number of containers. The continuous curve to the right of the sealed containers shows that the gauge pressure p2 fluctuates around zero at the end of the measurement for the sealed containers.

[0123] The measurement curves on the far left show the variation of test containers which were fitted with a 200 gm hole in the port area. A significant pressure loss is present here.

[0124] The middle dashed curve shows the variation in test containers with a hole in the port area measuring only 100 g / m. The variation in the pressure loss p2, which here correlates with a force loss of slightly less than 0.8 N, is clearly distinct from the variation in the measured values ​​of the sealed containers.

[0125] Therefore, leaks caused by an opening of only 100 mm in diameter can already be detected.

[0126] The measurement curves shown in Fig. 6 were recorded at a container temperature of 40°C.

[0127] Fig. 7 shows corresponding measurement curves to Fig. 6 for containers at 60°C.

[0128] As explained above, measurement becomes more problematic as the temperature of the container increases.

[0129] However, even with the 60°C warm containers, the dispersion range of the containers with a 100 gm hole (middle curve) is clearly distinct from the dense containers (right curve).

[0130] Fig. 8 is a flowchart of the process steps of a method according to the invention, based on an embodiment of the invention. First, an infusion bag is filled with a medicinal liquid and sealed. 201

[0131] The infusion bag is then placed in a secondary packaging and autoclaved in the sealed secondary packaging 202 .

[0132] The bag is then conveyed to the pressing device 203 and the pressing device is closed 204 until a pre-programmed force Fl is reached 205. The force Fl correlates with the desired pressure PI during pre-stretching.

[0133] According to one embodiment of the invention, the distance traveled by the pressing device is also measured simultaneously, or the distance that the pressing device can travel is limited by its design.

[0134] If the infusion bag is not filled at all or not completely filled, the force Fl will not be reached. This indicates a faulty bag, and the bag will be discarded. 206.

[0135] If the force Fl is reached, the pressing device is stopped and held for a programmed period of time 207.

[0136] The pressing device is then retracted until the force F2 is reached, which is less than Fl 208.

[0137] The force F2 correlates with the desired pressure p2 for the measuring window when testing for leaks.

[0138] F2 is now measured and corresponds to the restoring force exerted by the bag 209. It is measured whether F2 falls below a predetermined threshold value 210.

[0139] If this is the case, a leak is assumed and the bag is discarded 211.

[0140] If F2 does not fall below the threshold, the bag is fine and will be transported further 212.

[0141] Fig. 9 schematically shows an infusion bag 10 or an infusion bag 10 arranged in a secondary packaging 20, which includes at least one port 11a, 11b and which is pressurized by means of a pressing device.

[0142] In principle, the pressing device comprises two surfaces that can be moved towards each other, between which the infusion bag 10 is arranged.

[0143] The surfaces may, for example, have a bowl-shaped bulge, which is partially adapted to the contour of the infusion bag 10.

[0144] As the force applied by the pressing device increases, the infusion bag 10 must exert a corresponding restoring force. This increases the pressure inside the container.

[0145] Since such an infusion bag always also contains a gas volume, the pressure increase is accompanied by a compression of the gas volume.

[0146] If the pressing device is stopped and only the force is measured, gas or liquid will escape in the event of a leak and the pressure in the infusion bag 10 will drop, which can be detected by the force measurement.

[0147] Preferably, ports 11a and 11b are arranged facing upwards. They are then located within the gas volume. Leaks are most often found in the area of ​​ports 11a and 11b, which can be easily detected in this orientation.

[0148] Fig. 10 is a side view of an exemplary embodiment of a system 100 according to the invention for testing the tightness of containers 10.

[0149] In this exemplary embodiment, an infusion bag 10, inserted into a secondary packaging 20, lies in the receiving chamber of the system 100. The receiving chamber is bounded in one direction by the plate 103 and in the other direction by the conveyor belt 104.

[0150] The conveyor belt 104 can accommodate at least one, preferably several, infusion bags 10 in succession, above which a plate 103 is also arranged to form a pressing device (not shown).

[0151] The plate 103 can be moved via the actuator 102 towards the conveyor belt 104 and thus compress the infusion bag 10 arranged in the secondary packaging 20.

[0152] The force exerted by the actuator 102, which corresponds to the restoring force of the infusion bag 10, can be detected by the measuring cell 101, which is arranged between the plate 103 and the actuator 102. The actuator 102, measuring cell 101 and conveyor belt 104 are located on at least one arm 105, which can be pivoted via a pivot bearing 106 by means of a drive 107.

[0153] For this purpose, the arm 105 is pivotably arranged on a support 108.

[0154] Fig. 10 shows the horizontal position.

[0155] The horizontal bags are transported by an automation device (not shown) to conveyor belt 104.

[0156] As shown in Fig. 11, at least one arm 5, which is pivotably attached to the support 108, can then be pivoted by about 90° so that the pressing device formed from conveyor belt 104, actuator 102 and measuring cell 101 is arranged in a vertical position.

[0157] The infusion bag 10 is first pre-stretched under a pressure pl, as described above. Then, the leak test is performed at pressure p2.

[0158] After the measurement has been carried out, the arm 105 can be swung back into the horizontal position and the infusion bag(s) will be conveyed further via the conveyor belt 104.

[0159] Infusion bags with a leak can, for example, be subsequently sorted out using a sorting device.

[0160] The invention enables the simple detection of leaks, even in the pm range, in infusion bags. Reference list

[0161] 10 containers / infusion bags

[0162] I la, 11b Port

[0163] 12 lower part

[0164] 13 Top

[0165] 14 Snap-off cap

[0166] 15 Longitudinal weld seam

[0167] 16 transverse weld

[0168] 20 Secondary packaging

[0169] 21 Longitudinal weld seam

[0170] 22nd notch

[0171] 23 transverse weld

[0172] 100 plant

[0173] 101 measuring cell

[0174] 102 Actuator

[0175] 103 plate

[0176] 104 Conveyor belt

[0177] 105 Arm

[0178] 106 swivel bearings

[0179] 107 Drive

[0180] 108 carriers

[0181] Fill and seal 201 infusion bags.

[0182] Autoclave 202 infusion bags in secondary packaging

[0183] Transport 203 bags to the pressing device

[0184] 204 Pressing device assemble

[0185] 205 fl oz is reached

[0186] Sort out 206 bags

[0187] 207 Stop and hold the pressing device

[0188] 208 Retract the press device until F2 is reached

[0189] 209 F2 measure

[0190] 210 F2 falls below threshold

[0191] Sort out 211 bags

[0192] Move 212 bags onward

Claims

Claims:

1. Method for testing the tightness of a flexible container (10) filled with a liquid, in particular an infusion bag (10), wherein an overpressure pl is first generated in the container (10) by advancing a pressing device, so that the container (10) is pre-stretched, and wherein the pressing device is then retracted, and wherein after retraction of the pressing device a lower overpressure p2 compared to the overpressure pl is measured in the pre-stretched container (10), so that a leak can be determined on the basis of a measured pressure drop of p2 and / or a measured volume loss at p2 in the container (10).

2. Method according to the preceding claim, characterized in that the pressure drop in the container (10) is determined by a force applied to the pressing device.

3. Method according to one of the preceding claims, characterized in that the compression of the container (10) and the determination of the leakage are carried out in the same pressing device.

4. Method according to one of the preceding claims, characterized in that the pressing device is advanced until a force Fl is reached and then retracted until a force F2 is applied to the pressing device, in particular wherein Fl is 1.1 to 5 times, preferably 1.5 to 3.5 times, particularly preferably 1.8 to 2.8 times, which is as large as F2.

5. Method according to one of the preceding claims, characterized in that F2 lies between 20 and 300 N, in particular between 50 and 180 N.

6. Method according to one of the preceding claims, characterized in that the overpressure pl during pre-stretching is between 0.02 and 1 bar, preferably between 0.15 and 0.3 bar, particularly preferably between 0.20 and 0.25 bar, and / or that the overpressure p2 is between 0.02 and 1 bar, preferably between 0.05 and 0.3 bar, particularly preferably between 0.07 and 0.11 bar.

7. Method according to one of the preceding claims, characterized in that the container (10) is pre-stretched for 0.1 to 10 s, preferably 1 to 5 s, particularly preferably 2 to 3.5 s.

8. Method according to one of the preceding claims, characterized in that the overpressure p2 and / or the volume loss at p2 is measured over a time interval of 0.1 to 10 s, preferably from 1 to 5 s, particularly preferably from 2.5 to 4 s, and / or that the overpressure p2 and / or the volume loss at p2 is measured within less than 60 min, preferably within less than 5 min, particularly preferably within less than 1 min, after pre-expansion of the container.

9. Method according to one of the preceding claims, characterized in that, that the liquid in the container (10) during the measuring the overpressure p2 and / or the volume loss at p2 has a temperature of 30 to 80 °C, preferably 35 to 65 °C, and / or that the container (10) comprises at least one port (11a, 11b) which is oriented upwards at least during the measurement of the overpressure p2 and / or the volume loss at p2.

10. Method according to one of the preceding claims, characterized in that a container (10) is tested which is filled with 50 to 1000 ml of liquid and / or that a container (10) is tested which is formed from a multilayer film, in particular from a polypropylene film and / or the container (10) is provided sterile in a secondary packaging (20), in particular in a tear-open bag.

11. Use of a method according to any of the preceding claims for testing the tightness of containers (10) filled with a liquid, wherein leaking containers (10) are sorted out, in particular wherein containers (10) with an opening having a diameter of less than 150 pm (maximum diameter) are sorted out.

12. Container (10) , tested by a method according to one of the preceding claims.

13. System for testing the tightness of flexible containers filled with a liquid (10) comprising a receiving chamber for at least one container (10), a pressing device by means of which the liquid in the TI Containers (10) arranged in the receiving space can be compressed, wherein the pressing device comprises a force measuring device for measuring a pressing force acting on the container (10), and a control for carrying out a method according to one of the preceding claims.

14. System according to the preceding claim, characterized in that the receiving space together with the pressing device is pivotable between a horizontal and a vertical position.

15. System according to one of the preceding claims, characterized in that the receiving space is limited opposite the pressing device by a conveying device, in particular a conveyor belt (104) , for the container (10) and / or that the pressing device is formed by a movable plate (103).

16. System according to one of the preceding claims, characterized in that the force measuring device measures the force acting on the pressing device, in particular on the plate (103).

17. Use of a system according to one of the preceding claims for testing containers (10), in particular infusion bags (10), for leak tightness.

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